Process for preparing high antiknock gasoline



July 21, 1936. o. FITVZI slMoN PROCESS FOR PREPARING HIGH ANTIKNOCK GASOLINE Filed May 22, 1933 2 Sheets-Sheet 1 n my? N 2 M.

Jul 21, 193

O. F ITZ SIMONS 2 Sheets-Sheet 2 Filed May 22', 1953 bi .l O WW n W 2 .w w w ore mm w @m m aw O x 0 m o m m w .w w w w m w w 7 xtrant (Jtigh Octane) Eatimatcd INVENTOR fitnfigfiimo B 4% W ATTORNEY 7 Patented July 21, 1936 UNITED STATES PATENT OFFICE PROCESS FOR PREPARING HIGH ANTIKNQCK GASOLINE ration of Indiana Application May 22, 1933, Serial No. 672,122

8 Claims.

ticularly to improvements in the sulfur dioxideextraction process for producing high antiknock motor fuels.

It has long been known that certain solvents, such as sulfur dioxide, have the property of extracting naphthenic from parafllnic hydrocarbons iU ranging from gasoline to wax. In these processes the first extract is most naphthenic in nature and the raflinate is paraflinic. If the raflinate is reextracted it may be separated into a component which is more parafiinic than the first raflinate and another component which is less paraflinic than the first raflinate but more paraflinic than the first extract. In other words, by repeated extractions it has been possible to separate an oil into several fractions of gradually increasing paraflinicity. v

The present invention is not primarily concerned with the separation of paramnic from naphthenic components of a petroleum oil,'--it is specific to the gasoline fraction and it is concerned with the separation of high antiknock components from low antiknock components. In other words, the object of my invention is to prepare a high grade motor fuel from a low grade motor fuel, whether the low grade fuel is of petroleum origin or whether it comes from shale oil, the destructive distillation of carbonaceous materials, the distillation of petroleum, or the cracking, polymerization or hydrogenation of petroleum or carbonaceous products. More specifically, the object of my invention is to fractionate a. motor fuel into components of different knock ratings or octane numbers and to obtain maximum yields of motor fuels having extremely high octane numbers.

A further object of my invention is to adapt a sulfur dioxide extraction for use with motor fuels so that the yields of high antiknock gasoline will be increased and so that gasoline of higher octane number will be produced than have hitherto been produced by sulfur dioxide extraction (see U. S. 1,585,473 and 1,661,566). A further object is to provide a complete process for the preparation of high grade motor fuels, including stabilization and finishing treatments as well as fraclower than any temperatures heretofore used in solvent extraction processes. I have also discovered that there is a critical range in which products of maximum octane number are obtainable. .The first extracts have a considerably low- 5 er octane number than the extracts in this critical range, and the extracts beyond this range likewise have a lower octane number. Starting with a gasoline having an octane number of 62 and using amounts of sulfur dioxide necessary to 10 obtain varying amounts of extracts at 5 F. I have found that a 10% extract has an octane number of about 68, a 30% extract about 80, a 50% extract of about 79 and a extract of about 72 octane number. Operating in this manner it is impos- 15 sible to obtain an octane number higher than 81. However, if the first 10% extract is discarded and a suflicient amount of sulfur dioxide is added to effect the separation of the next 30% (based on original gasoline) I have discovered that much higher octanenumbers may be obtained.

I have also discovered that when the fractionation is effected at a temperature of 90 F. the first 10% fraction will have an octane number of about 86; the first 30% fraction of about 25 97, the first 50% fraction of about 89, and the first 70% fraction of about 76 octane number. In this case it will be observed that with the same yields of extracts I obtain very much higher antiknock ratings. A 30% extract at 50 F. had 30 a knock rating of only 80 while a 30% extract at had an octane rating of 97. Now if the first fraction is discarded in the low temperature extraction process I have discovered that motor fuels may be obtained with a knock rating ranging 35 from -110 octane number,a result which is heretofore unprecedented.

The invention will be more clearly understood by reference to the accom anying drawings which form a part of thisspecification and in which- Figure l is a diagrammatic plan of my improved system, and

Figure 2 is a graph showing the effect of different extraction temperatures and the use of amounts of sulfur dioxide to produce different amounts of extracts.

Sulfur dioxide from storage tank I0 is introduced by pipe ll through pump' l2 and pipe I3 to mixer II. The gasoline or motor fuel to be treated is introduced from any suitable storage tank through pipe l5 and heat exchanger !6, where it is cooled,-into said mixer, the combined mixture being introduced into cooler I]. This cooler may be provided with cooling coils for the circulation of brine or it may be jacketed so that cooling may be effected by the vaporization of carbon dioxide, ethane, propane, etc. from an external jacket. In the preferred embodiment, however, the refrigeration is effected by vaporizing a part of the sulfur dioxide, the sulfur dioxide vapors being withdrawn through pipe l8 by compressor l9 and forced through heat exchanger 20 or other suitable condensers or coolers back to storage tank ID. 'Itwill be understood that instead of using a single compressor I may compress the vapors in stages and I may maintain the temperature of the storage tank It! at any desired point by removing vapors from the upper part thereof, condensing them and reintroducing the condensed vapors into the storage tank.

The cooled mixture of sulfur dioxide and gasoline, which may be at 0 E, is introduced by-pipe 2| into separator 22, the extract being withdrawn through pipe 23 to a suitable stabilizing or stripping tower and the raflinate being transferred by pipe 24 to the base of countercurrent extractor 25.

Sulfur dioxide from storage tank in, pipe II and pump 12 is introduced by pipe 25 into cooler 21, which may consist of a heat exchange device or of a suitable tank from which vapors may be withdrawn through pipe 28 by compressor 29 and returned through heat exchanger 30 through pipe 3|. duced by pipe 32, pump 33 and pipe 34 to the upper part of the countercurrent extractor 25.

Extract from the base of the extractoris withdrawn through pipe 35 to a suitable stabilizing tower and the raflinate is withdrawn through pipe 35, heat exchanger 31 and heat exchanger 38 to stabilizing tower 39. Tower, 39 is equipped with a steam coil 40 at the base thereof with suitable fractionating and/0r stripping plates 4|. Vapors leave the top of this tower through pipe 42 and reflux is introduced at the top through pipe 43. The stabilized rafllnate is withdrawn from the base of the tower through pipe 44, heat exchanger 38 and pipe 45.

' The extract from extractor 25 passes through pipe 35, heat exchanger 45 and heat exchanger 41 to stabilizer tower 48, which contains steam coil 49, fractionating and/or stripping plates 50, vapor outlet 5| and reflux supply 52. The stabilized and/or stripped gasoline (extract) is withdrawn from the base of the tower through pipe 53 and it is passed through heat exchanger 41 and pipe 54 to a suitable storage tank. I

The extract from separator 22 is passed through pipe 23, heat exchanger 55 and heat exchanger 56 to stabilizer 51. This stabilizer is provided with heater coil 58, fractionating and/or stripping plates 59, vapor outlet 50 and reflux supply iii. The stabilized and stripped gasoline is withdrawn through pipe 62 and passed through heat exchanger 56 and pipe 53 to a suitable storage tank. I

Vaporconduits 42, 5| and 50 lead to vapor main 64, which leads to condenser 55 and collector 66. Gases are withdrawn from the top of this collector through pipe 51 and liquids are moved through pipe 68. This liquid may either be withdrawn through pipe 69 to a suitable storage tank and/or it may be circulated through pump 10 and reflux line H to supply reflux to the strippers through pipes 5|, 52 and 43. Gases from 61 are returned to storage drum l0 after compression and condensat'ion,-they may be introduced into pipe N.

For the sake of simplicity many of the heat The cooled sulfur dioxide is then introexchange systems have not been shown in detail. For instance, heat exchangers 46 and 55 may take the place of heat exchanger IS in the incoming gasoline line or, as shown by the drawings, wherein pipe I5 is brought in heat exchange relation with pipes 23 and 35 and wherein pipes 23 and 35 are operated in heat exchange relation with pipe l5. Likewise, pipe 36 may be in heat exchanged relation to pipe 3| or I5. Other heat exchange systems along these general lines may be employed.

The operation of my invention may be understood from a specific embodiment wherein a high grade motor fuel is prepared from cracked heavy naptha having an initial of 275 F., a maximum of 430 F. and an octane number of 62. In determining the octane numbers on reto 400 end point.

The invention will. first be described at an operating temperature of 5 F. The exact amount of sulfur dioxide mixed with the incoming naphtha will depend to a large extent on the design of heat exchange equipment and the insulation of the system, but sufficient sulfur dioxide should be added so that it will leave 55% by volume based on the incoming naphtha. When the mixture leaving cooler i1 is slightly below 5 F., about 5-10% of the naphtha charged will be withdrawn as extract in the sulfur dioxide 9 layer through pipe 23, this extract is simultaneously stabilized and stripped of sulfur dioxide in stabilizer tower 51 and it yields a motor fuel having an octane number of about 68.

The raflinate from pipe 24 is extracted with an additional amount of sulfur dioxide, which is preferably about IUD-150% by volume of the naphtha originally charged. The amount of sulfur dioxide in this case is not critical and it should be regulated to give an extract of about 30-50% of the volume of naphtha charged. This will yield a finished extract having an octane number of about while the highest possible suiting products, these products were redistilled octane number obtainable in a one-step extraction process would be about 81. By discarding the first fraction extracted I obtain a gasoline of higher knock rating than would otherwise be possible and at the same time I increase the yield of this high grade gasoline.

In my preferred embodiment I operate at extremely low temperature, preferably F.

In this case, considerably more sulfur dioxide.

will have to be mixed with the incoming naphtha in order that the temperature of the mixture leaving the cooler through pipe 2| shall be at this low temperature and at the same time retain enough sulfur dioxide to give an extract of about 5% or 10% of the volume ,of the naphtha charged.

This fraction will have an octane number of quality gasoline is about 30% of the volume of naphtha charged and a 40% yield with a single extraction step would only have an octane number of about 93.

y volume of the' Furthermore, the yield of this high The invention will be more clearly understood by reference to the graphs in Figure 2', showing the results of extracting 62 octane heavy naphtha at +5 F. In these graphs one line represents the yield and octane number obtainable in single extractions with varying quantities of sulphur dioxide to produce varying percentages of extract. The other line indicates the variation in yield and octane number of separate increments of gasoline which would be obtained by successive extraction of small increments, and is in fact a differential curve. It will be seen that the peak in the differential graph lies between extract percentages of about 10 and 40% yield, giving a yield of gasoline with an average octane number well above '75. In practicing my invention I segregate the components of the gasoline falling within the peak on the differential curves from the fractions which precede and follow said peak, and I thereby obtain higher I quality gasoline with larger yields than could otherwise be obtained.

Instead of increasing the amount of sulphur dioxide for the second extraction process and re-extracting the 'raflinate I may first use enough sulphur dioxide to'obtain an extract of about 50% of the gasoline charged, and I may then remove enough of the sulphur dioxide from the extract phase to cause about 30% or 40% thereof to separate out as rafiinate and to leave about 5% to 10% as a second extract. If the process is carried out in this way the second raflinate will have the extremely high antiknock value and the second extract will be a gasoline of intermediate knock rating.

. Also, it has been found that if the extraction is carried out in the presence of a hydrocarbon more volatile than gasoline, particularly ethane,

propane or butane, higher knock ratings can be produced than vcan possibly be produced by extraction with sulphur dioxide alone at the same temperatures,-even when a single extraction step is used. For instance, when one volume of propane, one volume of naphtha and two volumes of sulphur dioxide are intimately mixed and then separated at a temperature of about R, an extract is obtained which contains a considerable amount of propane, and when this extract is stabilized it is found to have knock ratings of -115. It has also been found that carbon dioxide admixed with sulphur dioxide makes it possible to obtain gasolines of higher knock ratings than could possibly be obtained by sulphur dioxide alone at any given temperature. The separation and segregation of a series of fractions of varying knock rating in the manner described herein is applicable to any of these solvents and solvent mixtures, as well as with other selective solvents.

The low antiknock raflinate from any of the above processes is not suitable for use as a motor fuel in internal combustion engines of modern design and therefore it should preferably be cracked or re-formed so' that by this thermal or pyrolytic process it may be converted into a high antiknock product. The re-formed heavy naphtha may be returned to the extraction process.

The extracts obtained in my system may require further treatment to remove the last traces of sulphur dioxide and to render them stable against oxidation, discolorization, gum formation, etc. These gasolines may be refined with a light sulfuric acid treatment, for example, with 75% acid, and they may be neutralized with alkali, sweetened with doctor or hypochlorite, or treated with 'clayin the vapor'phase either before or after the extraction process. Also, the gasoline may be stabilized by the addition of inhibitors, antioxidants or other dopes which are commonly used to prevent deterioration of high antiknock motor fuels.

While I have described in detail a preferred embodiment of my invention it should be understood that I do not limit myself to any of the details hereinabove set forth except as defined by the following claims which should be construed as broadly as the prior art will permit. For instance, the equipment for stripping the sulphur dioxide out of the various fractions will compressed, and it will therefore be introduced into one of the stages of the multistage compressor hereinabove referred to. Such expedients are familiar to those skilled in the art and they are therefore not described in detail.

I claim:

1. The method of separating a motor fuel into 1 components of higher and lower knock ratings than the original motor fuel, which comprises extracting said motor fuel with sulphur dioxide at a low temperature to obtain an extract of about 5% to 10% based on the volume of motor 'fuel charged, separating said extract from the ra'iiinate, extracting the raflinate with suflicient sulphur dioxide to produce an extract of about 20% to 50% of the motor fuel charged, separating said extract from the remaining components of the motor fuel, and removing sulphur dioxide from said second extract to produce a motor fuel of maximum, knock rating.

2. The method of separating a motor fuel into components of higher and lower knock ratings, than the original motor fuel which comprises admixing said motor fuel with liquefied sulphur dioxide, cooling said mixture to a temperature not higher than about 5 F., regulating the proportions of sulphur dioxide to motor fuel so that the cooled mixture will contain 55% sulphur dioxide by volume based on the motor fuel, separating the cooled mixture as a raifinate and an extract, adding about loo-% by volume (based on motor fuel originally charged) of liquid sulphur dioxide to' said raflinate, separating about 30% to 50% of the volume of motor fuel charged as extract in the added sulphur dioxide, and removing the sulphur dioxide from the extract to yield motor fuel of high anti-knock rating. I

3. The process of claim 2 wherein the cooling is obtained by vaporizing a normally gaseous refrigerant in the mixture with said motor fuel.

4. The method of obtaining a high antiknock motor fuel from cracked naphtha, which comprises adding a normally gaseous diluent to said naphtha and refrigerating said naphtha at very low temperature by vaporization of said diluent, extracting said cooled naphtha at a very low temperature with enough sulfur dioxide to give an extract of about 5% to 10% by volume of the naphtha charged, separating said extract from the raflinate, re-extracting said raflinate with a sufficient amount of sulfur dioxide to produce an extract of about 25% to 35% by volume of the naphtha charged, separating said extract from 75 the said rafilnate and separating the sulfur dioxide from the extract, finishing the extract to produce a high quality gasoline of high antiknock rating.

5. The method of obtaining a high antiknocl-r motor fuel from cracked naphtha, which comprises adding a normally gaseous diluent tc'rsaid naphtha and refrigerating said naphtha at very low temperature by vaporization of said diluent,

extracting said cooled naphtha at a very lowtemperature with enough sulfur dioxide to give an extract of about 5 to 10% by volume of the naphtha charged, separating the extract from the raiiinate, re-extracting said rafiinate countercurrently with a suflicient amount of sulfur dioxide to produce an extract of about 25% to 30% by volume of the naphtha charged, again separating said extract from said raflinate and sepav rating the sulfur dioxide from the extract and finishing the extract to produce a high quality gasoline of high antiknock 'rating.

6. The method of separating a motor fuel in components of higher and lower antiknock ratings than theoriginal motor fuel, which comprises extracting said motor fuel with liquid sulfur dioxide at a temperature not higher than about 5 F. to obtain an extract of about 5 to 10% basedon the volume of the motor fuel charged, separating said extract from the rafllnate, again extracting the railinate with suificient sulfur dioxide at a temperature of about -'l0 F. to F.

to produce an extract of about 20 to 50% ofthe .motor fuel, separating said extract from the remaining components and removing sulfur dioxide from the second extract to produce a motor fuel of maximum antiknock rating.

'7. Themethod of obtaining a high antiknock motor fuel from cracked naphtha, comprising adding a normally gaseous diluent having a volatility below that of the naphtha to said naphtha and refrigeratingsaid naphtha at a very low temperature by vaporizing a part of said diluent, extracting said cool naphtha at a temperature below about 5 F. with enough sulfur dioxide to give an extract of about 5 to by volume 01' the naphtha charged, separating said extract from the raflinate, re-extracting said rafflnate with a I suflicient amount of sulfur dioxide to produce an extract of about 25 to, 35% by volume of the naphtha charged, separating said extract from the said ramnate and separating the sulfur dioxide from the extract and finishing the extract to produce a high quality gasoline of high antiknock rating.

I 8. The method of separating cracked naphtha into components of higher and lower antiknock ratingsthan the original cracked naphtha, which comprises extracting said naphtha at "a very low temperature with enough sulfur dioxide to give an ex'tract'of about 5 to 10% by volume of the Y naphtha charged, separating the extract from the CERTIFICATE or CORRECTION.

Patent No. 2,048,522.

July 21, 19 36.

OGDEN F'ITZ SIMONS.

It is hereby certified that error appears in the printed specification of the above numbered patent rquiring correction as follows:

column, line 50, for !'of" readwith; and that the said Letters Patent "should Page 1, first be read with this correction therein that the same may conform to the record of the case in the Patent; Office.

Signed andsealed this 22nd day of September, A. D, 1936.

(Seal) Henry Van Ars'dale ActingCommissioner;of Patents.

the said rafilnate and separating the sulfur dioxide from the extract, finishing the extract to produce a high quality gasoline of high antiknock rating.

5. The method of obtaining a high antiknocl-r motor fuel from cracked naphtha, which comprises adding a normally gaseous diluent tc'rsaid naphtha and refrigerating said naphtha at very low temperature by vaporization of said diluent,

extracting said cooled naphtha at a very lowtemperature with enough sulfur dioxide to give an extract of about 5 to 10% by volume of the naphtha charged, separating the extract from the raiiinate, re-extracting said rafiinate countercurrently with a suflicient amount of sulfur dioxide to produce an extract of about 25% to 30% by volume of the naphtha charged, again separating said extract from said raflinate and sepav rating the sulfur dioxide from the extract and finishing the extract to produce a high quality gasoline of high antiknock 'rating.

6. The method of separating a motor fuel in components of higher and lower antiknock ratings than theoriginal motor fuel, which comprises extracting said motor fuel with liquid sulfur dioxide at a temperature not higher than about 5 F. to obtain an extract of about 5 to 10% basedon the volume of the motor fuel charged, separating said extract from the rafllnate, again extracting the railinate with suificient sulfur dioxide at a temperature of about -'l0 F. to F.

to produce an extract of about 20 to 50% ofthe .motor fuel, separating said extract from the remaining components and removing sulfur dioxide from the second extract to produce a motor fuel of maximum antiknock rating.

'7. Themethod of obtaining a high antiknock motor fuel from cracked naphtha, comprising adding a normally gaseous diluent having a volatility below that of the naphtha to said naphtha and refrigeratingsaid naphtha at a very low temperature by vaporizing a part of said diluent, extracting said cool naphtha at a temperature below about 5 F. with enough sulfur dioxide to give an extract of about 5 to by volume 01' the naphtha charged, separating said extract from the raflinate, re-extracting said rafflnate with a I suflicient amount of sulfur dioxide to produce an extract of about 25 to, 35% by volume of the naphtha charged, separating said extract from the said ramnate and separating the sulfur dioxide from the extract and finishing the extract to produce a high quality gasoline of high antiknock rating.

I 8. The method of separating cracked naphtha into components of higher and lower antiknock ratingsthan the original cracked naphtha, which comprises extracting said naphtha at "a very low temperature with enough sulfur dioxide to give an ex'tract'of about 5 to 10% by volume of the Y naphtha charged, separating the extract from the CERTIFICATE or CORRECTION.

Patent No. 2,048,522.

July 21, 19 36.

OGDEN F'ITZ SIMONS.

It is hereby certified that error appears in the printed specification of the above numbered patent rquiring correction as follows:

column, line 50, for !'of" readwith; and that the said Letters Patent "should Page 1, first be read with this correction therein that the same may conform to the record of the case in the Patent; Office.

Signed andsealed this 22nd day of September, A. D, 1936.

(Seal) Henry Van Ars'dale ActingCommissioner;of Patents. 

